1. Field of the Invention
The present invention relates to a driving circuit; particularly, the present invention relates to a source driving circuit utilized in a display.
2. Description of the Prior Art
A driving circuit is completed after the test process is performed to confirm the driving circuit is able to work properly. Taking a display device as an example, the display device has driving circuits including a source driving circuit, a gate driving circuit, etc. Since the driving circuit will directly affect the display quality, the test process for the driving circuit becomes more important as the display technology advances. Taking the test process for the source driving circuit as an example, because the load in a test machine is very small, the source driving circuit will generate an unstable output voltage when an output end of the source driving circuit is connected to the test machine. Please refer to an output voltage-time diagram illustrated in FIG. 1A. As shown in FIG. 1A, in the test process, after a period of time, the output voltage of a traditional driving circuit generates a ripple-like unstable wave instead of reaching to the stable status. This situation will affect the test process.
To address the problem mentioned above, the traditional technique utilizes two kinds of methods: one method is to have capacitance compensation in the operational amplifier of the source driving circuit; the other method is to have a resistor coupled to the output stage of the source driving circuit. However, the two methods will decrease response speed of the output voltage of the source driving circuit. Please refer to FIG. 1B that illustrates the output voltage-time diagram related to the output stage of the source driving circuit coupled to the resistor. As shown in FIG. 1B, compared to the slew rate of the source driving circuit without coupling the resistor (depicted as broken line), the slew rate of the output voltage (depicted as solid line) is notably decreased when the source driving circuit is coupled to the resistor. Consequently, when the source driving circuit is assembled to the display panel after the test process, the display device may have distorted output signals. Therefore, the structure of the traditional driving circuit needs to be improved.